High performance control of a permanent magnet synchronous machine with flux weakening operation

• Main Author: Yu, Yi.
• Other Authors: Gilbert Foo Hock Beng
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10356/54464
• Institution: Nanyang Technological University

This thesis investigates torque and flux control for the interior permanent magnet (IPM) synchronous motor. IPM synchronous motor has been used widely and practically in many fields, which range from the agriculture to industry. High performance and stable working state are highly required for the motor. Because most IPM synchronous motor is fed by the inverter, which offers 3-phase AC voltage from DC bus voltage, the SVPWM modulation is also widely applied for the IPMSM. Therefore, the SVPWM has been introduced. In this theory, the torque and flux control are via current controls in the rotor flux reference frame. The resultant stator voltage vector is determined by the nine switch states, among which there are six non-zero switch states and two zero switch states. Some important control techniques like ?���� ?���� = 0 control, ?���� ?���� ?���� ?���� = 1 control, MTPA control and MPO control are all introduced. Among them MTPA control, which is discussed specifically, is widely used in the PM synchronous motor speed control. It can produce maximum torque by the minimum current. Therefore, this control technique is often used for the motor when the rotor speed is lower than the basic speed. When the speed exceeds the cross speed and the motor is unloaded, the current vector is also controlled according to the trajectory of MTPA. Otherwise, the field weakening control technique is adopted. Due to the limit caused by the inverter, which offers 3-phase stator voltage to the motor, the value of the voltage and the current has the limit. Therefore, the current vector also should satisfy these limits. In dq reference frame, the trajectories of the voltage limit and current limit are an ellipse and a circle respectively. When the rotor speed is between the basic speed and the cross speed, the current vector should be controlled according to these limits both. Some simulations based on the simulink have been conducted to verify the effect of the cross-coupling and the process of the MTPA control. Given the tight deadline, some limits and drawbacks still exist. The simulation on the condition when the rotor speed exceeds the basic speed is not conducted yet. And the analysis of these techniques is not specific either.